Two-photon excitation of ethidium bromide labeled DNA

Henryk Malak, Felix N. Castellano, Ignacy Gryczynski, Joseph R. Lakowicz

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


We examined the steady state and time-resolved emission of DNA stained with ethidium bromide (EB) when excited with 90 fs pulses from a mode-locked titanium sapphire laser. Over the wavelength range from 840 to 880 nm EB-DNA was found to display two-photon excitation, with a cross-section near 7 X 10-50 cm4s/photon. Frequency-domain intensity decay measurements revealed similar multi-exponential intensity decays for one- and two-photon excitation. Time-resolved anisotropy decay measurements revealed similar correlation times, but different amplitudes as has been observed previously for two- versus one-photon excitation. These results indicate that two- photon excitation of EB-DNA can be accomplished with the fundamental output of a Ti:sapphire laser without obvious heating or perturbation of the DNA.

Original languageEnglish
Pages (from-to)35-41
Number of pages7
JournalBiophysical Chemistry
Issue number1-3
StatePublished - 1 Sep 1997


  • Chromosomes
  • DNA
  • Ethidium bromide
  • Fluorescence microscopy
  • Fluorescence spectroscopy
  • Imaging
  • Multi-photon microscopy
  • Three-photon excitation
  • Time-resolved fluorescence
  • Two-photon excitation


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